fix flag --enable-draw-occlusion

Users are now able to turn on draw occlusion by set flag enable draw occlusion
to true in chrome://flags.

TEST: build to chrome os device and verify if draw occlusion is turned on when
the flag is set to true.

Bug: 672929
Cq-Include-Trybots: master.tryserver.chromium.android:android_optional_gpu_tests_rel
Change-Id: Ibfca7fd5f91a8f7c04ea20db62029b0ab3a78870
Reviewed-on: https://chromium-review.googlesource.com/826103
Commit-Queue: Yi Xu <yiyix@chromium.org>
Reviewed-by: Tom Sepez <tsepez@chromium.org>
Reviewed-by: danakj <danakj@chromium.org>
Cr-Commit-Position: refs/heads/master@{#524088}

chrome/browser/about_flags.cc

@@ -1245,7 +1245,7 @@ const FeatureEntry kFeatureEntries[] = {
      SINGLE_VALUE_TYPE(switches::kShowOverdrawFeedback)},
     {"enable-draw-occlusion", flag_descriptions::kEnableDrawOcclusionName,
      flag_descriptions::kEnableDrawOcclusionDescription, kOsAll,
-     SINGLE_VALUE_TYPE(switches::kShowOverdrawFeedback)},
+     SINGLE_VALUE_TYPE(switches::kEnableDrawOcclusion)},
     {"ui-disable-partial-swap", flag_descriptions::kUiPartialSwapName,
      flag_descriptions::kUiPartialSwapDescription, kOsAll,
      SINGLE_DISABLE_VALUE_TYPE(switches::kUIDisablePartialSwap)},

services/viz/privileged/interfaces/compositing/renderer_settings.mojom

@@ -19,6 +19,7 @@ struct RendererSettings {
   ResourceSettings resource_settings;
   bool should_clear_root_render_pass;
   bool show_overdraw_feedback;
+  bool enable_draw_occlusion;
   int32 slow_down_compositing_scale_factor;
   bool use_skia_renderer;
 };

services/viz/privileged/interfaces/compositing/renderer_settings_struct_traits.cc

@@ -22,6 +22,7 @@ bool StructTraits<viz::mojom::RendererSettingsDataView, viz::RendererSettings>::
   out->gl_composited_overlay_candidate_quad_border =
       data.gl_composited_overlay_candidate_quad_border();
   out->show_overdraw_feedback = data.show_overdraw_feedback();
+  out->enable_draw_occlusion = data.enable_draw_occlusion();
   out->highp_threshold_min = data.highp_threshold_min();
   out->disallow_non_exact_resource_reuse =
       data.disallow_non_exact_resource_reuse();

services/viz/privileged/interfaces/compositing/renderer_settings_struct_traits.h

@@ -56,6 +56,10 @@ struct StructTraits<viz::mojom::RendererSettingsDataView,
     return input.show_overdraw_feedback;
   }
 
+  static bool enable_draw_occlusion(const viz::RendererSettings& input) {
+    return input.enable_draw_occlusion;
+  }
+
   static int highp_threshold_min(const viz::RendererSettings& input) {
     return input.highp_threshold_min;
   }

services/viz/privileged/interfaces/struct_traits_unittest.cc

@@ -41,6 +41,7 @@ TEST_F(StructTraitsTest, RendererSettings) {
   input.release_overlay_resources_after_gpu_query = true;
   input.gl_composited_overlay_candidate_quad_border = true;
   input.show_overdraw_feedback = true;
+  input.enable_draw_occlusion = true;
   input.highp_threshold_min = -1;
   input.disallow_non_exact_resource_reuse = true;
   input.use_skia_renderer = true;
@@ -68,6 +69,7 @@ TEST_F(StructTraitsTest, RendererSettings) {
   EXPECT_EQ(input.gl_composited_overlay_candidate_quad_border,
             output.gl_composited_overlay_candidate_quad_border);
   EXPECT_EQ(input.show_overdraw_feedback, output.show_overdraw_feedback);
+  EXPECT_EQ(input.enable_draw_occlusion, output.enable_draw_occlusion);
   EXPECT_EQ(input.highp_threshold_min, output.highp_threshold_min);
   EXPECT_EQ(input.disallow_non_exact_resource_reuse,
             output.disallow_non_exact_resource_reuse);

tools/metrics/histograms/enums.xml

@@ -25118,6 +25118,7 @@ from previous Chrome versions.
       label="AutofillToolkitViewsCreditCardDialogsMac:disabled"/>
   <int value="-802348444" label="disable-site-engagement-service"/>
   <int value="-798187384" label="try-supported-channel-layouts"/>
+  <int value="-795854288" label="enable-draw-occlusion"/>
   <int value="-795600188" label="disable-async-dns"/>
   <int value="-793921836" label="ShowAllDialogsWithViewsToolkit:disabled"/>
   <int value="-790036192" label="overscroll-start-threshold"/>